MONTAGNE: Countless videos have documented the craze of groups of people dancing wildly to the song "Harlem Shake." Now gone viral: a group of Colorado College students - one in a banana costume - crowded into the aisle of a Frontier flight. It does look like the plane might be shaking. The FAA is investigating, though a spokeswoman for Frontier Airlines says the seatbelt sign was off. It's MORNING EDITION. Transcript provided by NPR, Copyright NPR.